The invention relates to an acoustic absorber, an acoustic transducer, and a method for producing an acoustic absorber or an acoustic transducer.
It is known from the prior art to use open-pore porous materials for sound damping, with a “porous” material meaning a material having a specific proportion of cavity inclusions. An “open-pore” porous material is in particular a material in which the predominant proportion of the cavities in the material is in flow connection with other cavities. Owing to the interconnected cavities of the open-pore porous material, sound waves can thus enter the material and at least partially penetrate it.
The energy of the sound waves entering the open-pore porous material is at least partially converted into thermal energy in the material, in particular because the kinetic energy of air molecules that is associated with the sound wave is converted into heat on account of friction between the air molecules and the material surrounding the cavities. As a consequence of this absorption mechanism, sound waves of a shorter wavelength, i.e. a higher frequency, are absorbed more strongly than low frequencies.
Acoustic transducers, for example in the form of flat-panel loudspeakers, which however often have a strongly non-linear frequency characteristic, are furthermore known from the prior art.